Tag: classification of bryophytes

Mosses are characterized by a leafy gametophore with stem-like and leaf-like structures, the complete absence of true vascular tissues, and a filamentous juvenile gametophyte stage called the protonema. Therefore, all the given statements are correct.

The sporophyte (sporogonium) of Riccia is the simplest among bryophytes, consisting solely of a capsule. It completely lacks a foot and a seta.

Since the sporophyte of Riccia consists only of a capsule and lacks a stalk (seta), it remains completely embedded within the tissue of the gametophytic thallus.

Both Riccia and Marchantia (liverworts) have unicellular, unbranched rhizoids. These can be either smooth-walled or tuberculate, but they are always single-celled and do not branch.

The peristome teeth in moss capsules are hygroscopic structures that respond to changes in humidity, aiding in the gradual and effective dispersal of spores.

When a moss spore germinates, it first produces a filamentous, branched, green, and algal-like juvenile stage called the protonema, from which the leafy gametophores later develop.

The sporophyte of Anthoceros is unique because it possesses a basal intercalary meristematic zone situated between the foot and the capsule, which allows for continuous, indeterminate growth of the sporophyte.

Anthoceros (a hornwort) has mucilage cavities on the ventral surface of its thallus which are colonized by the nitrogen-fixing cyanobacterium Nostoc, forming a symbiotic relationship.

In all bryophytes, including Riccia, the sporophyte is physically attached to and nutritionally dependent (either partially or completely) on the dominant, independent gametophyte. Thus, the sporophyte is parasitic on the gametophyte.

In Anthoceros, the ventral surface of the thallus contains slime pores (mucilage clefts) through which mucilage is secreted, and these pores also serve as entry points for symbiotic Nostoc colonies.